docs: def moment_magnitude_scalar(moment):
      '''
      Uses Hanks & Kanamori formula for calculating moment magnitude from
      a scalar moment (Nm)
      '''
      if isinstance(moment, np.ndarray):
          return (2. / 3.) * (np.log10(moment) - 9.05)
      else:
          return (2. / 3.) * (log10(moment) - 9.05)